Soak the lentils for 3 hours in enough water to cover them by an inch, then drain before adding to the slow cooker.

If your slow cooker has a sauté function, use it to cook the onions, garlic and ginger with 2 tablespoon water. Otherwise, use a skillet, then transfer the aromatics to the slow cooker.

Add some salt and ground black pepper. Stir well and cook until the onions are translucent, adding a little water if needed to prevent sticking.

Add the greens and the tomato puree and mix well. Add the turmeric. Stir.

Drain the lentils and add them to the onions and greens and stir well to mix. Add four cups of water or vegetable stock and mix thoroughly. Add more salt and black pepper.

Put the lid on the crockpot and cook for about 5 hours on low, until the lentils have broken down and are tender. If the mixture gets dry during cooking, add more water.

When the dal has broken down thoroughly, stir the dal well with a ladle. Check for salt and add more if needed. Also add more black pepper if you have a taste for it-- I do.

Squeeze a few drops of lemon juice and add the coriander and stir well. Serve hot.